Background: Fine needle aspiration (FNA) cytologic diagnosis of bone lesions is controversial; opponents cite its low sensitivity and proponents emphasize its cost-effectiveness, specificity and rapid turnaround time. The focus of FNA cytology is most often to exclude malignancy, which may contribute to incomplete information sharing on the part of the health care team and the published low sensitivity of diagnostic cytology of osseous lesions. It is therefore incumbent upon cytopathologists to formulate a complete differential diagnosis of osseous lesions.
Case: A 72-year-old man, admitted for severe abdominal pain, underwent diagnostic computed tomography (CT) examination that incidentally revealed multiple abdominal and pelvic lytic bone lesions. CT-guided FNA of a lesion revealed bland histiocytic and spindled cells, prominent hemosiderin pigment and scattered multinucleated cells, findings consistent with osteitis fibrosa cystica. Subsequent consultation with the medical team revealed the patient's underlying secondary hyperparathyroidism.
Conclusion: This case emphasizes the importance of correlating clinical history and radiologic findings to the accurate cytologic diagnosis of bone lesions. The benign cytomorphologic features of brown tumor should not be overlooked or be considered nondiagnostic in the hunt for suspected malignancy. FNA allowed confident exclusion of a malignant process and prevented unnecessary surgery and its inherent risks.